Pattern inspection method and apparatus

ABSTRACT

A color image of an inspection object is taken by an imaging means capable of taking a color image to obtain color information of an RGB color space. A gray-scale image of a color component of the RGB color space or another color space is generated, and the inspection object is detected by a pattern recognition technique. Alternatively, a binary image is generated from the generated gray-scale image, and the inspection object is detected by performing pattern recognition on the binary image. Color data of a pixel occupied by the detected inspection object is compared with color data of a non-defective inspection object which is previously prepared to judge whether or not the inspection object is defective. In addition, this judgment result is reflected in another manufacturing step through a network and product quality is improved.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a pattern inspection method and apattern inspection apparatus in conducting an in-process inspection in amanufacturing process.

2. Description of the Related Art

Automation of various kinds of microscopy by image processing has beenadvanced in a manufacturing process of a semiconductor device. One ofmicroscopes used for inspection is an optical microscope; however, anautomated inspection by the optical microscope is limited to the casewhere an object is a circuit pattern or the like. Automation of opticalmicroscopy of an inspection object which has a finer structure than thecircuit pattern or the like has not been advanced so much. It is anactual condition where the optical microscopy is mainly performedvisually by an inspector.

Although a digital camera attached to an optical microscope or a lasermicroscope can take an image of an inspection object as a color image, amonochrome image is often used in image processing after taking animage. However, it is known that a subtle difference among inspectionobjects, which is difficult to distinguish with a monochrome image, canbe distinguished if a color image is used. Reference 1 is an examplewhere a color image is used for an appearance inspection (Reference 1:Japanese Patent Laid-Open No. 2004-125434).

As described above, optical microscopy in a manufacturing process iscurrently mainly conducted visually by an inspector. However, a visualinspection is also desired to be automated for cost reduction by furtherimprovement in efficiency.

SUMMARY OF THE INVENTION

The present invention is devised in order to solve the above-describedproblem, and it is an object of the present invention to provide aninspection method and an inspection apparatus which can simply andeasily judge an inspection object by taking an image of the inspectionobject over a substrate, generating data of the taken color image, andperforming image processing.

If image processing is performed on a color image, detailedcharacteristics of an inspection object can also be captured. Therefore,an automation of an inspection of an inspection object, which has notbeen intended for automation of inspection so far, can be expected.

In Reference 1, a microscope is not used, and a relatively largeelectronic circuit component is assumed as an inspection object. Theelectronic circuit component is an object having such a size as to beable to be inspected visually by an inspector.

The following measures are taken in the invention to achieve theabove-described object.

The present invention provides a pattern inspection method having thesteps of converting first color information including three colorcoordinate components, red (R), green (G), and blue (B), of an RGB colorspace obtained from a color image of an inspection surface over asubstrate into second color information including three color coordinatecomponents of another color space, and specifying the position of aninspection object and judging the inspection object based on the secondcolor information.

Note that one feature of the invention is that the position of theinspection object is specified based on a characteristic amount of animage obtained using the second color information, the position of theinspection object is specified using a first color coordinate componentselected from the second color information, and the inspection object isjudged by comparing a second color coordinate component selected fromthe second color information with preset color data of a non-defectiveunit (a reference color coordinate component of non-defective referencecolor information).

Specifically, a color image of an inspection substrate is taken first.In the present invention, a color image, which is taken using a digitalcamera attached to an optical microscope while a predetermined positionof the inspection substrate is irradiated with white light, can be used.Here, an imaging means is not limited to the optical microscope and thedigital camera as long as the image means can take a color image. Forexample, a laser microscope may be used instead of the opticalmicroscope.

The color image is transmitted from the digital camera to a computer andis stored in a memory of the computer. The color image has colorinformation including color coordinate components of an RGB color space(hereinafter referred to as first color information).

In the invention, second color information including color coordinatecomponents of a color space other than the RGB color space thereinafterreferred to as a second color space) is calculated from the first colorinformation of the color image, using a conversion formula, and thesecond color information is stored in the memory.

Here, the second color space may be any three-dimensional orfour-dimensional color space, and is not limited to a specific colorspace. For example, there is an HSB color space including three colorcomponents, hue, saturation, and brightness, or the like as the colorspace other than the RGB color space. However, since each color spacehas its own characteristic, a color space which can capturecharacteristics of the inspection object well may be appropriatelyselected as the second color space in converting the RGB color spaceinto the second color space.

After calculating the color information of the second color space, onecolor coordinate component (first color coordinate component) isselected from the color coordinate components of the second color spaceto generate a gray-scale image expressed by the value of the first colorcoordinate component. Here, as the first color coordinate component, acolor coordinate component which can capture characteristics of theinspection object well may be appropriately selected.

After generating the gray-scale image, image processing such as patternmatching is performed to detect all of the inspection objects includedin the gray-scale image. Simultaneously, coordinate data of each pixeloccupied by each inspection object is stored in the memory on a perinspection object basis. This males it possible to specify the positionof the inspection object.

The position of the inspection object may be specified not by performingimage processing such as pattern matching on the gray-scale image but bygenerating a binary image from the gray-scale image with a thresholdappropriately determined and performing pattern matching or the like onthe binary image.

After obtaining the coordinate data of the pixel occupied by theinspection object, another color coordinate component (second colorcoordinate component) is selected from the color coordinate componentsof the RGB color space or the second color space to take statistics ofthe second color coordinate component in the pixel occupied by theinspection object. Here, as the second color coordinate component, acomponent which distinctly shows whether or not the inspection object isdefective may be appropriately selected. Thereafter, the inspectionobject is judged by comparing the second color coordinate component anda reference color coordinate component of preset non-defective referencecolor information. Note that the judgment here may be performed by anappropriately-selected method, for example, by comparing histograms.

Note that the above-described conversion from the RGB color space intoanother color space is not limited to conversion into a single colorspace, and the RGB color space may be converted into a plurality ofcolor spaces. In other words, the RGB color space may be converted intoas many color spaces as needed to capture the characteristics of theinspection object.

In the case where it is not necessary to detect the inspection object bypattern recognition, such as when a color tone/coloration of the entiresubstrate is intended to be examined, the color information of thesecond color space may be analyzed without performing patternrecognition. In that case, the gray-scale image may not be generated, ifnot necessary.

In the invention, the judgment result is transmitted to another computersuch as a server through a network, and the judgment result is used asdata for judging manufacturing process conditions to determine themanufacturing process conditions. Accordingly, product quality can beimproved.

Further, the invention provides a pattern inspection apparatus using theabove-described pattern inspection method.

As described above, optical microscopy in a manufacturing process of asemiconductor device is currently mainly conducted visually by aninspector. However, if the pattern inspection method of the invention byimage processing is used, an automation of an inspection which has beendifficult to automate becomes possible, and labor saving and costreduction can be expected. In addition, since a color image, which hasnot so far been used so much in an automated inspection by imageprocessing, is used in the invention, a more detailed inspection thanever before becomes possible. Further, in the invention, the judgmentresult of inspection is transmitted to another computer through anetwork, and the judgment result is used as data for judgingmanufacturing process conditions to determine the manufacturing processconditions. Accordingly, product quality can be improved.

BRIEF DESCRIPTION OF DRAWINGS

The patent or application file contains at least one drawing executed incolor. Copies of this patent or patent application publication withcolor drawings will be provided by the Office upon request and paymentof the necessary fee.

FIG. 1 is a schematic diagram of an, inspection apparatus in oneembodiment of the present invention.

FIG. 2 is a flow chart showing an operation procedure of an inspectionmethod in the present invention.

FIGS. 3A to 3C respectively show an color image subjected to imageprocessing in the present invention, a cross-sectional view taken alongline A-A′ of FIG. 3A, and a magnified view of a lower portion of acontact hole 306.

FIGS. 4A and 4B show a gray-scale image and a binary image in thepresent invention.

FIG. 5 is a histogram of a gray-scale image in the present invention.

FIG. 6 shows a judgment result, whether or not a contact hole isdefective, by an inspection method of the present invention.

FIGS. 7A to 7E show examples of electronic appliances to which thepresent invention is applied.

DETAILED DESCRIPTION OF THE INVENTION

Hereinafter, a method for detecting defective etching of a contact holein a manufacturing process of a thin film transistor (hereinafterreferred to as a TFT) to which the present invention is applied isexplained as an embodiment mode of the invention. Since the embodimentmode to be explained hereinafter is one specific example of theinvention, various limitations are imposed. However, it is assumed thatthe present invention is not limited to these modes.

FIG. 1 is a schematic diagram showing a configuration of an inspectionapparatus in this embodiment mode. An optical lens 102 and coaxiallighting 103 are attached to a digital camera 101, and the digitalcamera 101 takes an image of an inspection substrate 110. The digitalcamera 101 takes not a monochrome image but a color image. The takenimage is magnified approximately 100 times by the optical lens 102. Thetaken image is transferred to a computer 104, and image processing isperformed in the computer 104. Various kinds of images can be checked ona monitor 105. The computer 104 is connected to another computer througha network 106.

The monitor 105 is used to display the taken image or like so as to bechecked visually by an inspector. However, the image processing isperformed in the computer 104, so the monitor 105 is only usedauxiliarily by the inspector.

Here, a method for manufacturing a TFT which is an inspection object toobtain a structure shown in FIG. 3B is explained. Note that a method formanufacturing a TFT is not limited to the method for manufacturing a TFTto be described here.

A base film 311 is formed over a substrate 310. As the substrate 310, asubstrate which can withstand a processing temperature in a subsequentmanufacturing process, such as a glass substrate of, for example, bariumborosilicate glass or alumino borosilicate glass, is used. As the basefilm 311, a silicon nitride oxide film is formed using a plasma CVDmethod to have a thickness of 10 nm to 400 nm (preferably, 50 nm to 300nm). Note that the base film 311 may be a single-layer insulating filmor a laminated layer of a plurality of insulating films.

Subsequently, a semiconductor film is formed over the base film 311. Thesemiconductor film is preferably formed without being exposed to theatmosphere after forming the base film 311. A thickness of thesemiconductor film is 20 nm to 200 nm (preferably, 40 nm to 170 nm).Note that the semiconductor film may be an amorphous semiconductor, asemi-amorphous semiconductor, or a polycrystalline semiconductor. Inaddition, silicon germanium as well as silicon can be used for thesemiconductor. In the case of using silicon germanium, a concentrationof germanium is preferably approximately 0.01 atomic % to 4.5 atomic %.

Note that a crystalline semiconductor film obtained by crystallizing anamorphous semiconductor film is used in this embodiment mode. As acrystallization method, there is a thermal crystallization method usingan electrically-heated furnace, a laser crystallization method usinglaser light, or a lamp annealing crystallization method using infraredlight. A crystallization method using a catalytic element canalternatively be used.

Although the semiconductor film is crystallized in this embodiment mode,an amorphous silicon film or a microcrystalline semiconductor film maybe directly subjected to a process to be described below without beingcrystallized. A semiconductor device using an amorphous semiconductor ora microcrystalline semiconductor has the advantage of lower cost andhigher yield since it requires fewer manufacturing steps than asemiconductor device using a polycrystalline semiconductor.

In addition, the above-described semi-amorphous semiconductor is a filmwhich includes a semiconductor having an intermediate structure betweenan amorphous semiconductor and a semiconductor having a crystallinestructure (including a single crystal and a polycrystal). Thissemi-amorphous semiconductor is a semiconductor having a third statewhich is stable in terms of free energy, and is a crystalline materialhaving short-range order and lattice distortion. The semi-amorphoussemiconductor-can be dispersed in a non-single crystal semiconductorwith a grain size of 0.5 nm to 20 nm.

Subsequently, the semiconductor film is processed to form anisland-shaped semiconductor film 312. Then, a gate insulating film 313is formed to cover the island-shaped semiconductor film 312, and aconductive film 314 to serve as a gate electrode or a wiring of a TFT isformed and patterned over the gate insulating film 313. Using, as amask, the conductive film 314 or a resist which is formed and processedinto a desired shape, the island-shaped semiconductor film 312 is dopedwith an impurity which imparts n-type conductivity to form animpurity-doped region 317 functioning as a source region, a drainregion, an LDD region, and the like. Note that a TFT 315 is formed to bean n-type here, but when the TFT is formed to be a p-type, an impuritywhich imparts p-type conductivity is added. According to the series ofsteps above, the TFT 315 can be formed.

Note that after forming the gate insulating film 313, a step ofhydrogenating the island-shaped semiconductor film 312 may be performedby performing heat treatment at 300° C. to 450° C. for 1 to 12 hours inan atmosphere containing hydrogen of 3% to 100%. As anotherhydrogenation method, plasma hydrogenation (using hydrogen excited byplasma) may be performed. According to this hydrogenation step, adangling bond can be terminated by thermally-excited hydrogen.

Subsequently, an interlayer insulating film 316 is formed to cover theTFT 315. Note that as a material for forming the interlayer insulatingfilm 316, an organic resin film, an inorganic insulating film, aninsulating film including a Si—O—Si bond formed using a siloxane-basedmaterial as a starting material (hereinafter referred to as asiloxane-based insulating film), or the like can be used. For thesiloxane-based insulating film, an organic group containing at leasthydrogen (for example, an alkyl group or aromatic hydrocarbon) is usedfor a substituent. A fluoro group may be used for a substitute.Alternatively, an organic group containing at least hydrogen, and afluoro group may be used for substituents.

Then, contact holes (301 to 307) are formed in the gate insulating film313 and the interlayer insulating film 316. Note that the contact holes(301 to 307) can be formed by performing etching using a mask formedfrom a resist or the like so as to expose the impurity-doped region 317and can be formed by either wet etching or dry etching. Note thatetching may be performed once or separately plural times depending onconditions. When etching is performed plural times, both wet etching anddry etching may be employed.

Through the above steps, the structure shown in FIG. 3B can be obtained.Note that a structure of a TFT to which the inspection method of theinvention can be applied is not limited to that shown in FIG. 3B.

The inspection in this embodiment mode means to inspect the structureshown in FIG. 3B and to inspect whether the contact holes (301 to 307)are formed to reach the conductive film 314. The contact holes 301, 303,304, and 305 are formed to reach the conductive film 314 or theimpurity-doped region 317, but the contact holes 302 and 306 are formedwithout reaching the conductive film 314 or the impurity-doped region317. In other words, the contact holes 302 and 306 are defects in thismanufacturing process. Note that only the contact holes which are formedwithout reaching the conductive film 314 or the impurity-doped region317 are described here; however, the case where a contact hole reachesthe base film 311 formed below the conductive film 314 (in other words,the case where a contact hole is formed to penetrate the conductive film314) can also be detected by the inspection method of the invention.

In the inspection method of the invention, such a defect as shown inFIG. 3B can be detected by using a predetermined method to process acolor image shown in FIG. 3A.

Note that by using the inspection method of the invention, it can bedetermined in accordance with a control criterion whether a TFTsubstrate in which a defect is detected is removed from a manufacturingprocess or continuously subjected to a subsequent step. In a subsequentstep, wirings to be connected to the conductive film 314 through thecontact holes are formed.

Note that, by further continuously performing a predetermined step afterforming the TFT, various semiconductor devices can be manufactured.

In addition, in the case where a defect can be repaired, even a TFTsubstrate which is considered as defective by the inspection can becontinuously subjected to a subsequent step after being repaired so asto be non-defective.

Subsequently, a contact hole to be inspected in this embodiment mode isexplained. In FIGS. 3A and 3B, the contact holes 301, 304, and 305 arecontact holes formed to reach the conductive film 314 formed over thebase film 311 and the gate insulating film 313 formed over the substrate310. In this case, when a contact hole is formed to reach the conductivefilm 314, the contact hole exhibits white. When a contact hole is formedwithout reaching the conductive film 314, the contact hole exhibitsbrown due to interference effect by the interlayer insulating film 316.Accordingly, in the case of inspecting this portion, it can bedetermined whether or not the contact holes 301, 304, and 305 reach theconductive film 314, in other words, whether or not the contact holesare defective, by converting a color space of the color image from anRGB color space into an HSB color space and using saturation (S) amongcolor coordinate components of the obtained HSB color space. This isbecause the saturation is increased as color of an object becomes vividand saturation of achromatic color (black, gray, or white) is zero;thus, color depth of the contact hole can be distinguished.

On the other hand, the contact holes 302, 303, 306, and 307 are contactholes formed to reach the impurity-doped region 317 formed over the basefilm 311 formed over the substrate 310.

In this embodiment mode, it is judged by the color of the contact holes302, 303, 306, and 307 whether the contact holes 302, 303, 306, and 307are formed to reach the impurity-doped region 317. The color of acontact hole differs depending on a laminated structure of a film formedbelow the contact hole. In the case of this embodiment mode, the colorappearance of the contact holes differs depending on film color of theimpurity-doped region 317 and film color of the gate insulating film 313formed below the contact holes.

FIG. 3C shows a magnified view in the vicinity of the contact hole 306of FIG. 3B. As to the semiconductor film in which the impurity-dopedregion 317 is formed, a film color thereof differs depending on athickness (l). Specifically, the semiconductor film exhibits pink whenthe thickness (l) is 66 nm or more; yellow, when 54 nm to less than 66nm; white; when 30 nm to 50 nm; blue, when 10 nm or less; and black,when less than 10 nm. Therefore, a change in color of a contact holewith a change in thickness of the impurity-doped region 317 in the caseof forming the contact hole is utilized. Incidentally, since thesemiconductor film is formed to have a thickness of 55 nm in thisembodiment mode, the contact hole exhibits yellow. The contact holes302, 303, 306, and 307 formed with little change in thickness of thesemiconductor film-exhibit yellow.

In the case of the contact holes 302 and 306 which do not reach theimpurity-doped region 317, the thickness (l) of the impurity-dopedregion 317 is not changed, but a thickness (m′) of the gate insulatingfilm 313 is changed compared to a thickness (m) before forming thecontact holes and color depth is changed. In other words, the contacthole 306 does not reach the impurity-doped region 317, but is formed toremove part of the gate insulating film 313. In other words, the gateinsulating film 313 thinly remains below the contact hole 306, and thethickness (m) is not zero. In such a case, the contact hole 306 exhibitsdeeper yellow than yellow of the contact holes 303 and 307. The contacthole 302 also exhibits deeper yellow than yellow of the contact holes303 and 307 since the gate insulating film 313 also remains belowthe-contact hole 302 as is the case with the contact hole 306.

Accordingly, also in the case of inspecting this portion, it can bedetermined, whether or not the contact hole is defective, by convertinga color space of the color image from an RGB color space into an HSBcolor space, and using saturation (S) among color coordinate componentsof the obtained HSB color space.

The gate insulating film 303 remains as below the contact holes 302 and506 due to defective etching. When the gate insulating film 313 remainsas described above, electrical connection cannot be obtained even when awiring is formed in a subsequent TFT manufacturing process, and a defectis caused. Therefore, it is necessary to perform an inspection afterforming the contact hole to determine whether the gate insulating film313 in a portion of the contact hole is removed by etching. By using theinspection method of the invention, it can be judged whether the gateinsulating film 313 is removed by etching, and manufacturing processconditions can be determined by using an inspection result as data forjudging manufacturing process conditions. Therefore, product quality canbe improved.

Hereinafter, a specific technique for the inspection method in thisembodiment mode is explained. FIG. 2 is a flow chart showing steps ofdetecting defective etching of a contact hole.

First, an inspection substrate is irradiated with the coaxial lighting103, and an optical microscope image of an inspection region over theinspection substrate is taken with the digital camera 101 and theoptical lens 102 (Step 1). In this embodiment mode, FIG. 3A is used as acolor image which is taken in Step 1. As described above, the contactholes 301, 303, 304, 305, and 307 are normally-etched contact boles,and-exhibit white or yellow as deep as silicon therearound. The contactholes 302 and 306 are contact holes in which the gate insulating film313 is not completely removed due to defective etching and defectiveopening is caused, and exhibit deeper yellow than silicon therearound.It is an object of this embodiment mode to judge the contact holes 302and 306 to be defective by examining color data of each contact holeafter detecting all contact holes in the image.

Pretreatment such as noise removal is performed on the color image (Step2).

The color image includes color coordinate components of an RGB colorspace, which is converted into an HSB color space including three colorcoordinate components, a hue (H), saturation (S); and brightness (B)(Step 3). Each color coordinate component of the HSB color space, whichis obtained by conversion, is stored in a memory. Since the HSB colorspace is a color space adjusted to a tendency for human to sense colorwith the naked eye, the HSB color space is more suitable than the RGBcolor space for human to interpret color of the image. For example, ifbrightness (B) is used, it can be judged whether an object is bright,and if saturation (S) is used, it can be judged whether color of anobject is vivid. It is difficult to make these judgments only with theRGB color space.

Subsequently, all contact holes (the contact holes 301 to 307) in thecolor image are detected (Step 4). In order to do so, brightness (B)among the color coordinate components of the HSB color space is used togenerate a gray-scale image expressed by the value of brightness. Thegenerated gray-scale image is shown in FIG. 4A. In addition, a histogramrepresenting the number of pixels to brightness of the gray-scale imageis FIG. 5. Since the brightness is high when it is bright and is lowwhen it is dark, brightness of the contact holes 301, 303, 304, 305, and307 which exhibit yellow in the color image and that of the contactholes 302 and 306 which exhibit white is high. Brightness is uniformlylow in a dark portion around each contact hole. Thus, it is suitable touse brightness in detecting all contact holes in the image regardless ofwhether or not the contact holes are defective. Therefore, brightness isused in this embodiment mode to generate the gray-scale image. However,a color coordinate component in generating the gray-scale image does notnecessarily need to be brightness, and may be appropriately selecteddepending on an inspection object.

Subsequently, a binary image is generated from the generated gray-scaleimage. Various techniques can be used to generate the binary image fromthe gray-scale image, but in this embodiment mode, a threshold isdetermined by a p-tile method to generate the binary image. The p-tilemethod is a method in which a value where a proportion of white pixelsto entire pixels in the binary image becomes p is regarded as athreshold using a histogram. In this embodiment mode, it is found bypreliminary analysis of a similar image that p is preferably 0.15. Thus,the p-tile method is performed with p=0.15. Consequently, the thresholdis calculated to be 140. The gray-scale image is binarized considering apixel having a brightness of less than 140 as black and a pixel havingbrightness of 140 or more as white to generate the binary image. Thegenerated binary image is shown in FIG. 4B. All contact holes (thecontact holes 301 to 307) become white connected regions in the binaryimage. Here, the connected region means a cluster of connected whitepixels in the binary image. Since brightness is small in a dark portionaround each contact hole, the dark portion becomes black in the binaryimage and functions to separate the contact hole from the peripheralconnected region. Thus, all contact holes are connected regions in thebinary image.

Subsequently, all connected regions in the binary image are detected bylabeling, and coordinate data of each pixel occupied by each connectedregion is stored in a memory. As for each detected connected region, acharacteristic amount with which characteristics of the contact hole canbe captured is calculated to sort out only a connected regioncorresponding to the contact hole. As the characteristic amount, anarea, a boundary length, degree of circularity, center of gravity, orthe like can be given. In this embodiment mode, an area and degree ofcircularity are used as the characteristic amount.

First, among the connected regions, only connected regions each havingan area close to that of the contact hole are selected. Here, the areais the number of pixels in the connected region. In this embodimentmode, only connected regions each having an area of 400 to 700 areselected.

Subsequently, as for each connected region selected in the precedingparagraph, degree of circularity is calculated to further sort out aconnected region having degree of circularity close to 1. Here, thedegree of circularity is an amount defined by 4πS/l² (S: area, l:boundary length) and becomes 1 in the case of a complete circle.

The above processing makes it possible to detect all contact holes(contact holes 301 to 307) in the taken image and to obtain coordinatedata of each pixel occupied by each contact hole. Note that the degreeof circularity of the connected region is calculated in this embodimentmode because the contact hole is circular. If an inspection object isnot circular, a method for capturing characteristics of the connectedregion may be changed in accordance with the shape. In addition,coordinate data of an inspection object may be obtained using atechnique such as pattern matching.

Subsequently, color data of each contact hole detected by the aboveprocessing is examined (Step 5). In this embodiment mode, as for each ofall contact holes (contact holes 301 to 307) detected by the processingto the preceding paragraph, a mean value per pixel of saturation (S) ofthe pixel occupied by the contact hole is calculated. For thecalculation of the mean value of saturation, saturation (S) among thecolor coordinate components of the HSB color space is used. As describedabove, the saturation is increased as color becomes more vivid andsaturation of achromatic color (black, gray, or white) is zero;therefore, the saturation is suitable for examining whether color of theobject is vivid. Since it can be judged, whether or not contact holeopening is defective, if vividness of a contact hole is examined,saturation is used as the color coordinate component in this embodimentmode. However, it may be determined which color coordinate component isused to judge whether or not contact hole opening is defective.

Lastly, the mean value of saturation (S) per pixel in each contact holeis compared with a preset reference value. If the mean value ofsaturation is smaller than the reference value, contact hole opening isjudged as not defective, and if larger, the contact hole opening isjudged as defective (Step 6). Here, it is assumed that the presetreference value is 190. A judgment result is shown in FM. 6. The contactholes 302 and 306 where defective etching has occurred are judged asdefective, and the contact holes 301, 303, 304, 305, and 307 wheredefective etching has not occurred are judged as not defective. In otherwords, it can be judged that in the contact holes 302 and 306, the-gateinsulating film 313 is not completely removed and defective contact holeopening has occurred. Note that electrical connection cannot be obtainedin the contact holes 302 and 306 which are defective in opening evenwhen the process is continued and a wiring is formed in a subsequentstep, which results in a defective substrate.

In this embodiment mode, this result can be transmitted to anothercomputer through a network 106, and manufacturing process conditions canbe determined by using the judgment result as data for judging themanufacturing process conditions. Accordingly, product quality can beimproved.

As described above, in the case of using the pattern inspection methodof the invention, a color image of an inspection object is taken first,and a color space is converted from an RGB color space into an HSB colorspace. Then, defective etching of a contact hole is inspected by usingtwo color coordinate components that are brightness (B) and saturation(S) among color information of the HSB color space which is obtained bythe conversion. Such an inspection cannot be conducted by imageprocessing of a monochrome image, and becomes possible by using a colorimage.

This embodiment mode is explained using a contact hole as an example.However, the inspection method of the invention can be applied to aninspection object having an uneven surface such as a columnar spacer ora reflecting electrode having a complex cross-sectional shape.

As described above, an appearance inspection which has been difficult-tobe automated can be automated by using the pattern inspection method ofthe invention. Note that the case of applying the inspection method ofthe invention to a manufacturing process of a TFT is described in thisembodiment mode. However, the invention is not limited thereto and canbe applied to manufacturing of all semiconductor devices (a liquidcrystal display device, an electroluminescent display, a plasma display,an integrated circuit, and the like).

Further, a color image is used in the invention; therefore, a moresubtle difference among inspection objects than ever before-can bedetected. In addition, in the invention, a judgment result of inspectioncan be transmitted to another computer through a network, andmanufacturing process conditions can be determined by using the judgmentresult as data for judging the manufacturing process conditions.Accordingly, product quality can be improved.

[Embodiment 1]

This embodiment describes examples of electronic appliances with a TFTinspected by an inspection method and/or an inspection apparatus of thepresent invention. As the electronic appliances, a camera such as avideo camera or a digital camera, a goggle type display (head mounteddisplay), a navigation system, a sound reproduction device (such as acar audio component), a notebook personal computer, a game machine, amobile information terminal (such as a mobile computer, a cellularphone, a mobile game machine, or an electronic book), an imagereproduction device equipped with a recording medium (specifically, adevice which reproduces a recording medium such as a digital versatiledisc (DVD) and is equipped with a display for displaying the image), andthe like are given. FIGS. 7A to 7E show the specific examples of theseelectronic appliances.

FIG. 7A shows a display device which corresponds to, for example, atelevision receiving device. The display device includes a case 2001, adisplay portion 2003, speaker portions 2004, and the like. The displaydevice in which the operating characteristic of a TFT is enhanced can bemanufactured when the display device is inspected by an inspectionmethod and/or an inspection apparatus of the present invention since aTFT without defective etching of a contact hole can be manufactured.

FIG. 7B shows a cellular phone, including a main body 2101, a case 2102,a display portion 2103, an audio input portion 2104, an audio outputportion 2105, operation keys 2106, an antenna 2108, and the like. Thecellular phone in which the operating characteristic of a TFT isenhanced can be manufactured when a substrate having the TFT included inthe cellular phone is inspected by an inspection method and/or aninspection apparatus of the present invention since a TFT withoutdefective etching of a contact hole can be manufactured.

FIG. 7C shows a notebook personal computer, including a main body 2201,a case 2202, a display portion 2203, a keyboard 2204, an externalconnection port 2205, a pointing mouse 2206, and the like. The notebookpersonal computer in which the operating characteristic of a TFT isenhanced can be manufactured when a substrate having the TFT included inthe notebook personal computer is inspected by an inspection methodand/or an inspection apparatus of the present invention since a TFTwithout defective etching of a contact hole can be manufactured.

FIG. 7D shows a mobile computer, including a main body 2301, a displayportion 2302, a switch 2303, operation keys 2304, an infrared port 2305,and the like. The mobile computer in which the operating characteristicof a TFT is enhanced can be manufactured when a substrate having the TFTincluded in the mobile computer is inspected by an inspection methodand/or an inspection apparatus of the present invention since a TFTwithout defective etching of a contact hole can be manufactured.

FIG. 7E shows a mobile game machine, including a case 2401, a displayportion 2402, speaker portions 2403, operation keys 2404, a recordingmedium inserting portion 15. 2405, and the like. The mobile game machinein which the operating characteristic of a TFT is enhanced can bemanufactured when a substrate having the TFT included in the mobile gamemachine is inspected by an inspection method and/or an inspectionapparatus of the present invention since a TFT without defective etchingof a contact hole can be manufactured.

As discussed above, the applicable range of the present invention is sowide that the present invention can be applied to electronic appliancesof various fields. In addition, the electronic appliances of thisembodiment can be freely combined with the embodiment.

This application is based on Japanese Patent Application serial No.2005-018004 filed in Japan Patent Office on Jan. 26, 2005, theentire-contents of which are hereby incorporated by reference.

1. A pattern inspection method comprising: magnifying and taking a colorimage including a plurality of pixels; generating a first colorinformation of each of the plurality of pixels, wherein the first colorinformation includes three color coordinate components, red (R), green(G), and blue (B), of an RGB color space; converting the first colorinformation of each of the plurality of pixels into a second colorinformation including three color coordinate components, hue (H),saturation (S), and brightness (B) of an HSB color space; generating agray-scale image in accordance with the brightness (B); generating abinary image from the gray-scale image by regarding one of the pluralityof pixels having a brightness (B) of less than a predetermined thresholdas black pixel and another one of the plurality of pixels having abrightness (B) of more than the predetermined threshold as a whitepixel; detecting an inspection object from the binary image by obtainingcoordinate data of at least two of the plurality of pixels overlapped bythe inspection object; and judging the inspection object by comparing areference saturation (S) of a preset non-defective reference colorinformation with a saturation (S) of the at least two of the pluralityof pixels.
 2. A pattern inspection method according to claim 1, whereindata of the color image is generated using a digital camera attached toan optical microscope or a laser microscope.
 3. A pattern inspectionmethod comprising: magnifying and taking a color image including aplurality of pixels; generating a first color information of each of theplurality of pixels, wherein the first color information includes threecolor coordinate components, red (R), green (G), and blue (B), of an RGBcolor space; converting the first color information of each of theplurality of pixels into a second color information including threecolor coordinate components, hue (H), saturation (S), and brightness (B)of an HSB color space; generating a gray-scale image in accordance withthe brightness (B); generating a binary image from the gray-scale imageby regarding one of the plurality of pixels having a brightness (B) ofless than a predetermined threshold as black pixel and another one ofthe plurality of pixels having a brightness (B) of more than thepredetermined threshold as a white pixel; detecting an inspection objectfrom the binary image by obtaining coordinate data of at least two ofthe plurality of pixels overlapped by the inspection object; calculatinga mean value of the saturation (S) of at least two of the plurality ofpixels overlapped by the inspection object, and comparing the mean valueof the saturation (S) in each inspection object with a preset saturation(S), and judging the inspection object.
 4. A pattern inspection methodaccording to claim 3, wherein data of the color image is generated usinga digital camera attached to an optical microscope or a lasermicroscope.
 5. A pattern inspection method comprising: magnifying andtaking a color image including a plurality of pixels; generating a firstcolor information of each of the plurality of pixels, wherein the firstcolor information includes three color coordinate components, red (R),green (G), and blue (B), of an RGB color space; converting the firstcolor information of each of the plurality of pixels into a second colorinformation including three color coordinate components, hue (H),saturation (S), and brightness (B) of an HSB color space; takingbrightness (B) which is suitable to specify a position of an inspectionobject from the second color information; specifying the position of theinspection object based on a characteristic amount of an image obtainedusing the brightness (B); and judging the inspection object by comparinga reference saturation (S) of preset non-defective reference colorinformation with a saturation (S) of the specified position.
 6. Apattern inspection method according to claim 5, wherein data of thecolor image is generated using a digital camera attached to an opticalmicroscope or a laser microscope.
 7. A pattern inspection methodcomprising: magnifying and taking a color image including a plurality ofpixels; generating a first color information of each of the plurality ofpixels, wherein the first color information includes three colorcoordinate components, red (R), green (G), and blue (B), of an RGB colorspace; converting the first color information of each of the pluralityof pixels into a second color information including three colorcoordinate components, hue (H), saturation (S), and brightness (B) of anHSB color space; taking brightness (B) which is suitable to specify aposition of an inspection object from the second color information;specifying the position of the inspection object based on acharacteristic amount of an image obtained using the brightness (B);calculating a mean value of the saturation (S) of at least two of theplurality of pixels overlapped by the object; and comparing the meanvalue of the saturation (S) in each inspection object with a presetsaturation (S), and judging the inspection object.
 8. A patterninspection method according to claim 7, wherein data of the color imageis generated using a digital camera attached to an optical microscope ora laser microscope.
 9. A method for manufacturing semiconductor devicecomprising: forming an inspection object over a substrate; after formingthe inspection object over the substrate, magnifying and taking a colorimage including a plurality of pixels; generating a first colorinformation of each of the plurality of pixels, wherein the first colorinformation includes three color coordinate components, red (R), green(G), and blue (B), of an RGB color space; converting the first colorinformation of each of the plurality of pixels into a second colorinformation including three color coordinate components, hue (H),saturation (S), and brightness (B) of an HSB color space; takingbrightness (B) which is suitable to specify a position of the inspectionobject from the second color information; specifying the position of theinspection object based on a characteristic amount of an image obtainedusing the brightness (B); and judging the inspection object by comparinga reference saturation (S) of preset non-defective reference colorinformation with a saturation (S) of the specified position.
 10. Themethod for manufacturing semiconductor device according to claim 9,wherein the inspection object is any one of a contact hole, a spacer anda reflecting electrode.